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Maternal Fever and Neural Tube Defects

Expectant mothers need to keep their cool -- high temperatures can pose a risk to the developing fetus.

Maternal hyperthermia during the first trimester seems to contribute to an increased risk for neural tube defects (NTDs). Animal studies in the 1980s suggested that fever might lead to NTDs; in humans, however, this association was harder to confirm. A case-control study was undertaken to investigate an epidemic of NTDs near the Mexican border in Texas.

Mexican-American mothers of infants born with NTDs in 14 Texas counties during 1995-2000 were compared with randomly selected control mothers, matched by hospital and year, who gave birth to live children without NTDs. About 6 weeks postpartum, the investigators interviewed mothers concerning their prenatal experiences with fevers, febrile illnesses, exposure to heat from external sources, and hyperthermia-inducing activities.

The findings revealed a two- to threefold increased risk for NTDs in the offspring of women who reported prenatal illness with fever; exposure to hot tubs, saunas, or electric blankets; exposure to environments of high heat, such as a hot kitchen; and work or exercise in the sun.

Comment: Women often do not know they are pregnant at the time the neural tube is closing (i.e., 2 weeks after the first missed period). When congenital anomalies such as NTDs occur, it is important for pediatricians to take a careful history of predisposing environmental causes. There seem to be sufficient data now to indicate that maternal hyperthermia conveys an increased risk for NTDs. Maternal temperature over 38.5°C (101.3°F) is of concern in early embryogenesis.

— Judith G. Hall, OC, MD

Published in Journal Watch Pediatrics and Adolescent Medicine January 14, 2005

Citation(s):

Suarez L et al. The effect of fever, febrile illness, and heat exposures on the risk of neural tube defects in a Texas-Mexico border population. Birth Defects Res A Clin Mol Teratol 2004 Oct; 70:815-9.

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